To improve manufacturing efficiency and reduce product costs, various attempts have been make in recent years to develop integrated insulating glass/window frame production systems.
One example which is described in a presentation given at InterGlass Metal 97' was developed in Germany by Meeth Fenester. With this production system, the window is, fabricated from plastic channel window frame profiles that are assembled around an insulating glass (IG) unit and corner welded using conventional hot plate technology. During the assembly process, the unit is held in position by means of a hot melt butyl adhesive bead that is located centrally in the frame channel. Twin silicone thermosetting glazing sealant beads are then applied in the two gaps either side of the IG unit. After assembly, the windows are stored in a truck container ready for shipping and the truck containers are left-parked outside the factory for a few hours while the two-part silicone sealant is cured. For the Meeth production system, there are four main drawbacks. First, because of the butyl adhesive bead, the glazing channel cannot be drained and this creates potential IG durability problems. Second, conventional hot plate welding is a slow process that is complicated by the need for corner flash removal. Third, the sash frame assemblies cannot be shipped until the two-part thermosetting sealant is fully cured. Fourth, the Meeth production is largely a manual process with manual loading of the individual frame profiles into the welding clamping fixtures and manual application of the sealant beads.
A second example of an integrated IG/window frame system is described in U.S. Pat. No. 5,622,017 issued to Lynn et al. and assigned to the Andersen Corporation. As with the Meeth system, the Andersen window is also fabricated from plastic channel frame profiles that are assembled around an IG unit and corner welded using conventional hot plate technology. In comparison with the Meeth System, the Andersen profile incorporates conventional plastic glazing fins on one side of the channel frame profile. A structural thermosetting sealant is then applied to one side of the unit and the single glazing sealant bead is allowed to cure. Because the IG glass unit is not held in position, the frame subassembly cannot be moved for several hours while waiting for the sealant to cure. In addition, the unit cannot be accurately centered within the channel profile and so the process of sealant application cannot be easily automated.
As described in U.S. Pat. No. 5,902,657 issued to Hanson et al., the channel frame profiles can be joined at the corners using friction welding with a moveable U-shaped metal platen that rapidly moves back and forth melting the plastic at the interface joint. As with conventional hot plate welding, the metal platen is then removed and the matching ends of the framing profiles are then pressured against each other. From a practical perspective, this solution is difficult to implement because as the metal plate is removed, the molten plastic material is also removed resulting in a poor weld assembly. A further concern is that the IG unit is held in position by the sloped channel walls and as a result there are potential glass breakage problems at the corners.
A third example of an integrated IG/window frame system is described in PCT application CA02/000842 by Field et al (See FIGS. 21-23 therein). Again, the frame assembly is welded using friction welding but instead of using a metal platen, a plastic web is used that is vibrated back and forth using an inverted vibratory welding head. To avoid potential glass breakage problems, the IG unit is isolated from the plastic channel frame profiles using conventional rubber setting blocks. However, because the unit is not firmly held in position and is not accurately centered, the sealant application process cannot easily be automated. In addition, the profiles have to be manually loaded into the clamping fixtures and this slows down the production cycle time.